{
	/*******************************************************************************
	 * Copyright (c) 2013 IBM Corp.
	 *
	 * All rights reserved. This program and the accompanying materials
	 * are made available under the terms of the Eclipse Public License v1.0
	 * and Eclipse Distribution License v1.0 which accompany this distribution. 
	 *
	 * The Eclipse Public License is available at 
	 *    http://www.eclipse.org/legal/epl-v10.html
	 * and the Eclipse Distribution License is available at 
	 *   http://www.eclipse.org/org/documents/edl-v10.php.
	 *
	 * Contributors:
	 *    Andrew Banks - initial API and implementation and initial documentation
	 *******************************************************************************/
	
	
	// Only expose a single object name in the global namespace.
	// Everything must go through this module. Global Paho.MQTT module
	// only has a single public function, client, which returns
	// a Paho.MQTT client object given connection details.
	 
	/**
	 * Send and receive messages using web browsers.
	 * <p> 
	 * This programming interface lets a JavaScript client application use the MQTT V3.1 or
	 * V3.1.1 protocol to connect to an MQTT-supporting messaging server.
	 *  
	 * The function supported includes:
	 * <ol>
	 * <li>Connecting to and disconnecting from a server. The server is identified by its host name and port number. 
	 * <li>Specifying options that relate to the communications link with the server, 
	 * for example the frequency of keep-alive heartbeats, and whether SSL/TLS is required.
	 * <li>Subscribing to and receiving messages from MQTT Topics.
	 * <li>Publishing messages to MQTT Topics.
	 * </ol>
	 * <p>
	 * The API consists of two main objects:
	 * <dl>
	 * <dt><b>{@link Paho.MQTT.Client}</b></dt>
	 * <dd>This contains methods that provide the functionality of the API,
	 * including provision of callbacks that notify the application when a message
	 * arrives from or is delivered to the messaging server,
	 * or when the status of its connection to the messaging server changes.</dd>
	 * <dt><b>{@link Paho.MQTT.Message}</b></dt>
	 * <dd>This encapsulates the payload of the message along with various attributes
	 * associated with its delivery, in particular the destination to which it has
	 * been (or is about to be) sent.</dd>
	 * </dl> 
	 * <p>
	 * The programming interface validates parameters passed to it, and will throw
	 * an Error containing an error message intended for developer use, if it detects
	 * an error with any parameter.
	 * <p>
	 * Example:
	 * 
	 * <code><pre>
	client = new Paho.MQTT.Client(location.hostname, Number(location.port), "clientId");
	client.onConnectionLost = onConnectionLost;
	client.onMessageArrived = onMessageArrived;
	client.connect({onSuccess:onConnect});
	
	function onConnect() {
	  // Once a connection has been made, make a subscription and send a message.
	  console.log("onConnect");
	  client.subscribe("/World");
	  message = new Paho.MQTT.Message("Hello");
	  message.destinationName = "/World";
	  client.send(message); 
	};
	function onConnectionLost(responseObject) {
	  if (responseObject.errorCode !== 0)
		console.log("onConnectionLost:"+responseObject.errorMessage);
	};
	function onMessageArrived(message) {
	  console.log("onMessageArrived:"+message.payloadString);
	  client.disconnect(); 
	};	
	 * </pre></code>
	 * @namespace Paho.MQTT 
	 */
	let utils = (typeof global != 'undefined')? global.utils :window.utils;
	if (typeof Paho === "undefined") {
		var Paho = {};
	}
	
	Paho.MQTT = (function (global) {
	
		// Private variables below, these are only visible inside the function closure
		// which is used to define the module. 
	
		var version = "@VERSION@";
		var buildLevel = "@BUILDLEVEL@";
		
		/** 
		 * Unique message type identifiers, with associated
		 * associated integer values.
		 * @private 
		 */
		var MESSAGE_TYPE = {
			CONNECT: 1, 
			CONNACK: 2, 
			PUBLISH: 3,
			PUBACK: 4,
			PUBREC: 5, 
			PUBREL: 6,
			PUBCOMP: 7,
			SUBSCRIBE: 8,
			SUBACK: 9,
			UNSUBSCRIBE: 10,
			UNSUBACK: 11,
			PINGREQ: 12,
			PINGRESP: 13,
			DISCONNECT: 14
		};
		
		// Collection of utility methods used to simplify module code 
		// and promote the DRY pattern.  
	
		/**
		 * Validate an object's parameter names to ensure they 
		 * match a list of expected variables name for this option
		 * type. Used to ensure option object passed into the API don't
		 * contain erroneous parameters.
		 * @param {Object} obj - User options object
		 * @param {Object} keys - valid keys and types that may exist in obj. 
		 * @throws {Error} Invalid option parameter found. 
		 * @private 
		 */
		var validate = function(obj, keys) {
			for (var key in obj) {
				if (obj.hasOwnProperty(key)) {       		
					if (keys.hasOwnProperty(key)) {
						if (typeof obj[key] !== keys[key])
						   throw new Error(format(ERROR.INVALID_TYPE, [typeof obj[key], key]));
					} else {	
						var errorStr = "Unknown property, " + key + ". Valid properties are:";
						for (var key in keys)
							if (keys.hasOwnProperty(key))
								errorStr = errorStr+" "+key;
						throw new Error(errorStr);
					}
				}
			}
		};
	
		/**
		 * Return a new function which runs the user function bound
		 * to a fixed scope. 
		 * @param {function} User function
		 * @param {object} Function scope  
		 * @return {function} User function bound to another scope
		 * @private 
		 */
		var scope = function (f, scope) {
			return function () {
				return f.apply(scope, arguments);
			};
		};
		
		/** 
		 * Unique message type identifiers, with associated
		 * associated integer values.
		 * @private 
		 */
		var ERROR = {
			OK: {code:0, text:"AMQJSC0000I OK."},
			CONNECT_TIMEOUT: {code:1, text:"AMQJSC0001E Connect timed out."},
			SUBSCRIBE_TIMEOUT: {code:2, text:"AMQJS0002E Subscribe timed out."}, 
			UNSUBSCRIBE_TIMEOUT: {code:3, text:"AMQJS0003E Unsubscribe timed out."},
			PING_TIMEOUT: {code:4, text:"AMQJS0004E Ping timed out."},
			INTERNAL_ERROR: {code:5, text:"AMQJS0005E Internal error. Error Message: {0}, Stack trace: {1}"},
			CONNACK_RETURNCODE: {code:6, text:"AMQJS0006E Bad Connack return code:{0} {1}."},
			SOCKET_ERROR: {code:7, text:"AMQJS0007E Socket error:{0}."},
			SOCKET_CLOSE: {code:8, text:"AMQJS0008I Socket closed."},
			MALFORMED_UTF: {code:9, text:"AMQJS0009E Malformed UTF data:{0} {1} {2}."},
			UNSUPPORTED: {code:10, text:"AMQJS0010E {0} is not supported by this browser."},
			INVALID_STATE: {code:11, text:"AMQJS0011E Invalid state {0}."},
			INVALID_TYPE: {code:12, text:"AMQJS0012E Invalid type {0} for {1}."},
			INVALID_ARGUMENT: {code:13, text:"AMQJS0013E Invalid argument {0} for {1}."},
			UNSUPPORTED_OPERATION: {code:14, text:"AMQJS0014E Unsupported operation."},
			INVALID_STORED_DATA: {code:15, text:"AMQJS0015E Invalid data in local storage key={0} value={1}."},
			INVALID_MQTT_MESSAGE_TYPE: {code:16, text:"AMQJS0016E Invalid MQTT message type {0}."},
			MALFORMED_UNICODE: {code:17, text:"AMQJS0017E Malformed Unicode string:{0} {1}."},
		};
		
		/** CONNACK RC Meaning. */
		var CONNACK_RC = {
			0:"Connection Accepted",
			1:"Connection Refused: unacceptable protocol version",
			2:"Connection Refused: identifier rejected",
			3:"Connection Refused: server unavailable",
			4:"Connection Refused: bad user name or password",
			5:"Connection Refused: not authorized"
		};
	
		/**
		 * Format an error message text.
		 * @private
		 * @param {error} ERROR.KEY value above.
		 * @param {substitutions} [array] substituted into the text.
		 * @return the text with the substitutions made.
		 */
		var format = function(error, substitutions) {
			var text = error.text;
			if (substitutions) {
			  var field,start;
			  for (var i=0; i<substitutions.length; i++) {
				field = "{"+i+"}";
				start = text.indexOf(field);
				if(start > 0) {
					var part1 = text.substring(0,start);
					var part2 = text.substring(start+field.length);
					text = part1+substitutions[i]+part2;
				}
			  }
			}
			return text;
		};
		
		//MQTT protocol and version          6    M    Q    I    s    d    p    3
		var MqttProtoIdentifierv3 = [0x00,0x06,0x4d,0x51,0x49,0x73,0x64,0x70,0x03];
		//MQTT proto/version for 311         4    M    Q    T    T    4
		var MqttProtoIdentifierv4 = [0x00,0x04,0x4d,0x51,0x54,0x54,0x04];
		
		/**
		 * Construct an MQTT wire protocol message.
		 * @param type MQTT packet type.
		 * @param options optional wire message attributes.
		 * 
		 * Optional properties
		 * 
		 * messageIdentifier: message ID in the range [0..65535]
		 * payloadMessage:	Application Message - PUBLISH only
		 * connectStrings:	array of 0 or more Strings to be put into the CONNECT payload
		 * topics:			array of strings (SUBSCRIBE, UNSUBSCRIBE)
		 * requestQoS:		array of QoS values [0..2]
		 *  
		 * "Flag" properties 
		 * cleanSession:	true if present / false if absent (CONNECT)
		 * willMessage:  	true if present / false if absent (CONNECT)
		 * isRetained:		true if present / false if absent (CONNECT)
		 * userName:		true if present / false if absent (CONNECT)
		 * password:		true if present / false if absent (CONNECT)
		 * keepAliveInterval:	integer [0..65535]  (CONNECT)
		 *
		 * @private
		 * @ignore
		 */
		var WireMessage = function (type, options) { 	
			this.type = type;
			for (var name in options) {
				if (options.hasOwnProperty(name)) {
					this[name] = options[name];
				}
			}
		};
		
		WireMessage.prototype.encode = function() {
			// Compute the first byte of the fixed header
			var first = ((this.type & 0x0f) << 4);
			
			/*
			 * Now calculate the length of the variable header + payload by adding up the lengths
			 * of all the component parts
			 */
	
			var remLength = 0;
			var topicStrLength = new Array();
			var destinationNameLength = 0;
			
			// if the message contains a messageIdentifier then we need two bytes for that
			if (this.messageIdentifier != undefined)
				remLength += 2;
	
			switch(this.type) {
				// If this a Connect then we need to include 12 bytes for its header
				case MESSAGE_TYPE.CONNECT:
					switch(this.mqttVersion) {
						case 3:
							remLength += MqttProtoIdentifierv3.length + 3;
							break;
						case 4:
							remLength += MqttProtoIdentifierv4.length + 3;
							break;
					}
	
					remLength += UTF8Length(this.clientId) + 2;
					if (this.willMessage != undefined) {
						remLength += UTF8Length(this.willMessage.destinationName) + 2;
						// Will message is always a string, sent as UTF-8 characters with a preceding length.
						var willMessagePayloadBytes = this.willMessage.payloadBytes;
						if (!(willMessagePayloadBytes instanceof Uint8Array))
							willMessagePayloadBytes = new Uint8Array(payloadBytes);
						remLength += willMessagePayloadBytes.byteLength +2;
					}
					if (this.userName != undefined)
						remLength += UTF8Length(this.userName) + 2;	
					if (this.password != undefined)
						remLength += UTF8Length(this.password) + 2;
				break;
	
				// Subscribe, Unsubscribe can both contain topic strings
				case MESSAGE_TYPE.SUBSCRIBE:	        	
					first |= 0x02; // Qos = 1;
					for ( var i = 0; i < this.topics.length; i++) {
						topicStrLength[i] = UTF8Length(this.topics[i]);
						remLength += topicStrLength[i] + 2;
					}
					remLength += this.requestedQos.length; // 1 byte for each topic's Qos
					// QoS on Subscribe only
					break;
	
				case MESSAGE_TYPE.UNSUBSCRIBE:
					first |= 0x02; // Qos = 1;
					for ( var i = 0; i < this.topics.length; i++) {
						topicStrLength[i] = UTF8Length(this.topics[i]);
						remLength += topicStrLength[i] + 2;
					}
					break;
	
				case MESSAGE_TYPE.PUBREL:
					first |= 0x02; // Qos = 1;
					break;
	
				case MESSAGE_TYPE.PUBLISH:
					if (this.payloadMessage.duplicate) first |= 0x08;
					first  = first |= (this.payloadMessage.qos << 1);
					if (this.payloadMessage.retained) first |= 0x01;
					destinationNameLength = UTF8Length(this.payloadMessage.destinationName);
					remLength += destinationNameLength + 2;	   
					var payloadBytes = this.payloadMessage.payloadBytes;
					remLength += payloadBytes.byteLength;  
					if (payloadBytes instanceof ArrayBuffer)
						payloadBytes = new Uint8Array(payloadBytes);
					else if (!(payloadBytes instanceof Uint8Array))
						payloadBytes = new Uint8Array(payloadBytes.buffer);
					break;
	
				case MESSAGE_TYPE.DISCONNECT:
					break;
	
				default:
					;
			}
	
			// Now we can allocate a buffer for the message
	
			var mbi = encodeMBI(remLength);  // Convert the length to MQTT MBI format
			var pos = mbi.length + 1;        // Offset of start of variable header
			var buffer = new ArrayBuffer(remLength + pos);
			var byteStream = new Uint8Array(buffer);    // view it as a sequence of bytes
	
			//Write the fixed header into the buffer
			byteStream[0] = first;
			byteStream.set(mbi,1);
	
			// If this is a PUBLISH then the variable header starts with a topic
			if (this.type == MESSAGE_TYPE.PUBLISH)
				pos = writeString(this.payloadMessage.destinationName, destinationNameLength, byteStream, pos);
			// If this is a CONNECT then the variable header contains the protocol name/version, flags and keepalive time
			
			else if (this.type == MESSAGE_TYPE.CONNECT) {
				switch (this.mqttVersion) {
					case 3:
						byteStream.set(MqttProtoIdentifierv3, pos);
						pos += MqttProtoIdentifierv3.length;
						break;
					case 4:
						byteStream.set(MqttProtoIdentifierv4, pos);
						pos += MqttProtoIdentifierv4.length;
						break;
				}
				var connectFlags = 0;
				if (this.cleanSession) 
					connectFlags = 0x02;
				if (this.willMessage != undefined ) {
					connectFlags |= 0x04;
					connectFlags |= (this.willMessage.qos<<3);
					if (this.willMessage.retained) {
						connectFlags |= 0x20;
					}
				}
				if (this.userName != undefined)
					connectFlags |= 0x80;
				if (this.password != undefined)
					connectFlags |= 0x40;
				byteStream[pos++] = connectFlags; 
				pos = writeUint16 (this.keepAliveInterval, byteStream, pos);
			}
	
			// Output the messageIdentifier - if there is one
			if (this.messageIdentifier != undefined)
				pos = writeUint16 (this.messageIdentifier, byteStream, pos);
	
			switch(this.type) {
				case MESSAGE_TYPE.CONNECT:
					pos = writeString(this.clientId, UTF8Length(this.clientId), byteStream, pos); 
					if (this.willMessage != undefined) {
						pos = writeString(this.willMessage.destinationName, UTF8Length(this.willMessage.destinationName), byteStream, pos);
						pos = writeUint16(willMessagePayloadBytes.byteLength, byteStream, pos);
						byteStream.set(willMessagePayloadBytes, pos);
						pos += willMessagePayloadBytes.byteLength;
						
					}
				if (this.userName != undefined)
					pos = writeString(this.userName, UTF8Length(this.userName), byteStream, pos);
				if (this.password != undefined) 
					pos = writeString(this.password, UTF8Length(this.password), byteStream, pos);
				break;
	
				case MESSAGE_TYPE.PUBLISH:	
					// PUBLISH has a text or binary payload, if text do not add a 2 byte length field, just the UTF characters.	
					byteStream.set(payloadBytes, pos);
						
					break;
	
	//    	    case MESSAGE_TYPE.PUBREC:	
	//    	    case MESSAGE_TYPE.PUBREL:	
	//    	    case MESSAGE_TYPE.PUBCOMP:	
	//    	    	break;
	
				case MESSAGE_TYPE.SUBSCRIBE:
					// SUBSCRIBE has a list of topic strings and request QoS
					for (var i=0; i<this.topics.length; i++) {
						pos = writeString(this.topics[i], topicStrLength[i], byteStream, pos);
						byteStream[pos++] = this.requestedQos[i];
					}
					break;
	
				case MESSAGE_TYPE.UNSUBSCRIBE:	
					// UNSUBSCRIBE has a list of topic strings
					for (var i=0; i<this.topics.length; i++)
						pos = writeString(this.topics[i], topicStrLength[i], byteStream, pos);
					break;
	
				default:
					// Do nothing.
			}
	
			return buffer;
		}	
	
		function decodeMessage(input,pos) {
		    var startingPos = pos;
			var first = input[pos];
			var type = first >> 4;
			var messageInfo = first &= 0x0f;
			pos += 1;
			
	
			// Decode the remaining length (MBI format)
	
			var digit;
			var remLength = 0;
			var multiplier = 1;
			do {
				if (pos == input.length) {
				    return [null,startingPos];
				}
				digit = input[pos++];
				remLength += ((digit & 0x7F) * multiplier);
				multiplier *= 128;
			} while ((digit & 0x80) != 0);
			
			var endPos = pos+remLength;
			if (endPos > input.length) {
			    return [null,startingPos];
			}
	
			var wireMessage = new WireMessage(type);
			switch(type) {
				case MESSAGE_TYPE.CONNACK:
					var connectAcknowledgeFlags = input[pos++];
					if (connectAcknowledgeFlags & 0x01)
						wireMessage.sessionPresent = true;
					wireMessage.returnCode = input[pos++];
					break;
				
				case MESSAGE_TYPE.PUBLISH:     	    	
					var qos = (messageInfo >> 1) & 0x03;
								
					var len = readUint16(input, pos);
					pos += 2;
					var topicName = parseUTF8(input, pos, len);
					pos += len;
					// If QoS 1 or 2 there will be a messageIdentifier
					if (qos > 0) {
						wireMessage.messageIdentifier = readUint16(input, pos);
						pos += 2;
					}
					
					var message = new Paho.MQTT.Message(input.subarray(pos, endPos));
					if ((messageInfo & 0x01) == 0x01) 
						message.retained = true;
					if ((messageInfo & 0x08) == 0x08)
						message.duplicate =  true;
					message.qos = qos;
					message.destinationName = topicName;
					wireMessage.payloadMessage = message;	
					break;
				
				case  MESSAGE_TYPE.PUBACK:
				case  MESSAGE_TYPE.PUBREC:	    
				case  MESSAGE_TYPE.PUBREL:    
				case  MESSAGE_TYPE.PUBCOMP:
				case  MESSAGE_TYPE.UNSUBACK:    	    	
					wireMessage.messageIdentifier = readUint16(input, pos);
					break;
					
				case  MESSAGE_TYPE.SUBACK:
					wireMessage.messageIdentifier = readUint16(input, pos);
					pos += 2;
					wireMessage.returnCode = input.subarray(pos, endPos);	
					break;
			
				default:
					;
			}
					
			return [wireMessage,endPos];	
		}
	
		function writeUint16(input, buffer, offset) {
			buffer[offset++] = input >> 8;      //MSB
			buffer[offset++] = input % 256;     //LSB 
			return offset;
		}	
	
		function writeString(input, utf8Length, buffer, offset) {
			offset = writeUint16(utf8Length, buffer, offset);
			stringToUTF8(input, buffer, offset);
			return offset + utf8Length;
		}	
	
		function readUint16(buffer, offset) {
			return 256*buffer[offset] + buffer[offset+1];
		}	
	
		/**
		 * Encodes an MQTT Multi-Byte Integer
		 * @private 
		 */
		function encodeMBI(number) {
			var output = new Array(1);
			var numBytes = 0;
	
			do {
				var digit = number % 128;
				number = number >> 7;
				if (number > 0) {
					digit |= 0x80;
				}
				output[numBytes++] = digit;
			} while ( (number > 0) && (numBytes<4) );
	
			return output;
		}
	
		/**
		 * Takes a String and calculates its length in bytes when encoded in UTF8.
		 * @private
		 */
		function UTF8Length(input) {
			var output = 0;
			for (var i = 0; i<input.length; i++) 
			{
				var charCode = input.charCodeAt(i);
					if (charCode > 0x7FF)
					   {
						  // Surrogate pair means its a 4 byte character
						  if (0xD800 <= charCode && charCode <= 0xDBFF)
							{
							  i++;
							  output++;
							}
					   output +=3;
					   }
				else if (charCode > 0x7F)
					output +=2;
				else
					output++;
			} 
			return output;
		}
		
		/**
		 * Takes a String and writes it into an array as UTF8 encoded bytes.
		 * @private
		 */
		function stringToUTF8(input, output, start) {
			var pos = start;
			for (var i = 0; i<input.length; i++) {
				var charCode = input.charCodeAt(i);
				
				// Check for a surrogate pair.
				if (0xD800 <= charCode && charCode <= 0xDBFF) {
					var lowCharCode = input.charCodeAt(++i);
					if (isNaN(lowCharCode)) {
						throw new Error(format(ERROR.MALFORMED_UNICODE, [charCode, lowCharCode]));
					}
					charCode = ((charCode - 0xD800)<<10) + (lowCharCode - 0xDC00) + 0x10000;
				
				}
				
				if (charCode <= 0x7F) {
					output[pos++] = charCode;
				} else if (charCode <= 0x7FF) {
					output[pos++] = charCode>>6  & 0x1F | 0xC0;
					output[pos++] = charCode     & 0x3F | 0x80;
				} else if (charCode <= 0xFFFF) {    				    
					output[pos++] = charCode>>12 & 0x0F | 0xE0;
					output[pos++] = charCode>>6  & 0x3F | 0x80;   
					output[pos++] = charCode     & 0x3F | 0x80;   
				} else {
					output[pos++] = charCode>>18 & 0x07 | 0xF0;
					output[pos++] = charCode>>12 & 0x3F | 0x80;
					output[pos++] = charCode>>6  & 0x3F | 0x80;
					output[pos++] = charCode     & 0x3F | 0x80;
				};
			} 
			return output;
		}
		
		function parseUTF8(input, offset, length) {
			var output = "";
			var utf16;
			var pos = offset;
	
			while (pos < offset+length)
			{
				var byte1 = input[pos++];
				if (byte1 < 128)
					utf16 = byte1;
				else 
				{
					var byte2 = input[pos++]-128;
					if (byte2 < 0) 
						throw new Error(format(ERROR.MALFORMED_UTF, [byte1.toString(16), byte2.toString(16),""]));
					if (byte1 < 0xE0)             // 2 byte character
						utf16 = 64*(byte1-0xC0) + byte2;
					else 
					{ 
						var byte3 = input[pos++]-128;
						if (byte3 < 0) 
							throw new Error(format(ERROR.MALFORMED_UTF, [byte1.toString(16), byte2.toString(16), byte3.toString(16)]));
						if (byte1 < 0xF0)        // 3 byte character
							utf16 = 4096*(byte1-0xE0) + 64*byte2 + byte3;
									else
									{
									   var byte4 = input[pos++]-128;
									   if (byte4 < 0) 
							throw new Error(format(ERROR.MALFORMED_UTF, [byte1.toString(16), byte2.toString(16), byte3.toString(16), byte4.toString(16)]));
									   if (byte1 < 0xF8)        // 4 byte character 
											   utf16 = 262144*(byte1-0xF0) + 4096*byte2 + 64*byte3 + byte4;
						   else                     // longer encodings are not supported  
							throw new Error(format(ERROR.MALFORMED_UTF, [byte1.toString(16), byte2.toString(16), byte3.toString(16), byte4.toString(16)]));
									}
					}
				}  
	
					if (utf16 > 0xFFFF)   // 4 byte character - express as a surrogate pair
					  {
						 utf16 -= 0x10000;
						 output += String.fromCharCode(0xD800 + (utf16 >> 10)); // lead character
						 utf16 = 0xDC00 + (utf16 & 0x3FF);  // trail character
					  }
				output += String.fromCharCode(utf16);
			}
			return output;
		}
		
		/** 
		 * Repeat keepalive requests, monitor responses.
		 * @ignore
		 */
		var Pinger = function(client, window, keepAliveInterval) { 
			this._client = client;        	
			this._window = window;
			this._keepAliveInterval = keepAliveInterval*1000;     	
			this.isReset = false;
			
			var pingReq = new WireMessage(MESSAGE_TYPE.PINGREQ).encode(); 
			
			var doTimeout = function (pinger) {
				return function () {
					return doPing.apply(pinger);
				};
			};
			
			/** @ignore */
			var doPing = function() { 
				if (!this.isReset) {
					this._client._trace("Pinger.doPing", "Timed out");
					this._client._disconnected( ERROR.PING_TIMEOUT.code , format(ERROR.PING_TIMEOUT));
				} else {
					this.isReset = false;
					this._client._trace("Pinger.doPing", "send PINGREQ");
					this._client.socket.send(pingReq); 
					this.timeout = this._window.setTimeout(doTimeout(this), this._keepAliveInterval);
				}
			}
	
			this.reset = function() {
				this.isReset = true;
				this._window.clearTimeout(this.timeout);
				if (this._keepAliveInterval > 0)
					this.timeout = setTimeout(doTimeout(this), this._keepAliveInterval);
			}
	
			this.cancel = function() {
				this._window.clearTimeout(this.timeout);
			}
		 }; 
	
		/**
		 * Monitor request completion.
		 * @ignore
		 */
		var Timeout = function(client, window, timeoutSeconds, action, args) {
			this._window = window;
			if (!timeoutSeconds)
				timeoutSeconds = 30;
			
			var doTimeout = function (action, client, args) {
				return function () {
					return action.apply(client, args);
				};
			};
			this.timeout = setTimeout(doTimeout(action, client, args), timeoutSeconds * 1000);
			
			this.cancel = function() {
				this._window.clearTimeout(this.timeout);
			}
		}; 
		
		/*
		 * Internal implementation of the Websockets MQTT V3.1 client.
		 * 
		 * @name Paho.MQTT.ClientImpl @constructor 
		 * @param {String} host the DNS nameof the webSocket host. 
		 * @param {Number} port the port number for that host.
		 * @param {String} clientId the MQ client identifier.
		 */
		var ClientImpl = function (uri, host, port, path, clientId) {
			// Check dependencies are satisfied in this browser.
			if (!("WebSocket" in global && global["WebSocket"] !== null)) {
				throw new Error(format(ERROR.UNSUPPORTED, ["WebSocket"]));
			}
			if (!("localStorage" in global && global["localStorage"] !== null)) {
				throw new Error(format(ERROR.UNSUPPORTED, ["localStorage"]));
			}
			if (!("ArrayBuffer" in global && global["ArrayBuffer"] !== null)) {
				throw new Error(format(ERROR.UNSUPPORTED, ["ArrayBuffer"]));
			}
			this._trace("Paho.MQTT.Client", uri, host, port, path, clientId);
	
			this.host = host;
			this.port = port;
			this.path = path;
			this.uri = uri;
			this.clientId = clientId;
	
			// Local storagekeys are qualified with the following string.
			// The conditional inclusion of path in the key is for backward
			// compatibility to when the path was not configurable and assumed to
			// be /mqtt
			this._localKey=host+":"+port+(path!="/mqtt"?":"+path:"")+":"+clientId+":";
	
			// Create private instance-only message queue
			// Internal queue of messages to be sent, in sending order. 
			this._msg_queue = [];
	
			// Messages we have sent and are expecting a response for, indexed by their respective message ids. 
			this._sentMessages = {};
	
			// Messages we have received and acknowleged and are expecting a confirm message for
			// indexed by their respective message ids. 
			this._receivedMessages = {};
	
			// Internal list of callbacks to be executed when messages
			// have been successfully sent over web socket, e.g. disconnect
			// when it doesn't have to wait for ACK, just message is dispatched.
			this._notify_msg_sent = {};
	
			// Unique identifier for SEND messages, incrementing
			// counter as messages are sent.
			this._message_identifier = 1;
			
			// Used to determine the transmission sequence of stored sent messages.
			this._sequence = 0;
			
	
			// Load the local state, if any, from the saved version, only restore state relevant to this client.   	
			for (var key in localStorage)
				if (   key.indexOf("Sent:"+this._localKey) == 0  		    
					|| key.indexOf("Received:"+this._localKey) == 0)
				this.restore(key);
		};
	
		// Messaging Client public instance members. 
		ClientImpl.prototype.host;
		ClientImpl.prototype.port;
		ClientImpl.prototype.path;
		ClientImpl.prototype.uri;
		ClientImpl.prototype.clientId;
	
		// Messaging Client private instance members.
		ClientImpl.prototype.socket;
		/* true once we have received an acknowledgement to a CONNECT packet. */
		ClientImpl.prototype.connected = false;
		/* The largest message identifier allowed, may not be larger than 2**16 but 
		 * if set smaller reduces the maximum number of outbound messages allowed.
		 */ 
		ClientImpl.prototype.maxMessageIdentifier = 65536;
		ClientImpl.prototype.connectOptions;
		ClientImpl.prototype.hostIndex;
		ClientImpl.prototype.onConnectionLost;
		ClientImpl.prototype.onMessageDelivered;
		ClientImpl.prototype.onMessageArrived;
		ClientImpl.prototype.traceFunction;
		ClientImpl.prototype._msg_queue = null;
		ClientImpl.prototype._connectTimeout;
		/* The sendPinger monitors how long we allow before we send data to prove to the server that we are alive. */
		ClientImpl.prototype.sendPinger = null;
		/* The receivePinger monitors how long we allow before we require evidence that the server is alive. */
		ClientImpl.prototype.receivePinger = null;
		
		ClientImpl.prototype.receiveBuffer = null;
		
		ClientImpl.prototype._traceBuffer = null;
		ClientImpl.prototype._MAX_TRACE_ENTRIES = 100;
	
		ClientImpl.prototype.connect = function (connectOptions) {
			var connectOptionsMasked = this._traceMask(connectOptions, "password"); 
			this._trace("Client.connect", connectOptionsMasked, this.socket, this.connected);
			
			if (this.connected) 
				throw new Error(format(ERROR.INVALID_STATE, ["already connected"]));
			if (this.socket)
				throw new Error(format(ERROR.INVALID_STATE, ["already connected"]));
			
			this.connectOptions = connectOptions;
			
			if (connectOptions.uris) {
				this.hostIndex = 0;
				this._doConnect(connectOptions.uris[0]);  
			} else {
				this._doConnect(this.uri);  		
			}
			
		};
	
		ClientImpl.prototype.subscribe = function (filter, subscribeOptions) {
			this._trace("Client.subscribe", filter, subscribeOptions);
				  
			if (!this.connected)
				throw new Error(format(ERROR.INVALID_STATE, ["not connected"]));
			
			var wireMessage = new WireMessage(MESSAGE_TYPE.SUBSCRIBE);
			wireMessage.topics=[filter];
			if (subscribeOptions.qos != undefined)
				wireMessage.requestedQos = [subscribeOptions.qos];
			else 
				wireMessage.requestedQos = [0];
			
			if (subscribeOptions.onSuccess) {
				wireMessage.onSuccess = function(grantedQos) {subscribeOptions.onSuccess({invocationContext:subscribeOptions.invocationContext,grantedQos:grantedQos});};
			}
	
			if (subscribeOptions.onFailure) {
				wireMessage.onFailure = function(errorCode) {subscribeOptions.onFailure({invocationContext:subscribeOptions.invocationContext,errorCode:errorCode});};
			}
	
			if (subscribeOptions.timeout) {
				wireMessage.timeOut = new Timeout(this, window, subscribeOptions.timeout, subscribeOptions.onFailure
						, [{invocationContext:subscribeOptions.invocationContext, 
							errorCode:ERROR.SUBSCRIBE_TIMEOUT.code, 
							errorMessage:format(ERROR.SUBSCRIBE_TIMEOUT)}]);
			}
			
			// All subscriptions return a SUBACK. 
			this._requires_ack(wireMessage);
			this._schedule_message(wireMessage);
		};
	
		/** @ignore */
		ClientImpl.prototype.unsubscribe = function(filter, unsubscribeOptions) {  
			this._trace("Client.unsubscribe", filter, unsubscribeOptions);
			
			if (!this.connected)
			   throw new Error(format(ERROR.INVALID_STATE, ["not connected"]));
			
			var wireMessage = new WireMessage(MESSAGE_TYPE.UNSUBSCRIBE);
			wireMessage.topics = [filter];
			
			if (unsubscribeOptions.onSuccess) {
				wireMessage.callback = function() {unsubscribeOptions.onSuccess({invocationContext:unsubscribeOptions.invocationContext});};
			}
			if (unsubscribeOptions.timeout) {
				wireMessage.timeOut = new Timeout(this, window, unsubscribeOptions.timeout, unsubscribeOptions.onFailure
						, [{invocationContext:unsubscribeOptions.invocationContext,
							errorCode:ERROR.UNSUBSCRIBE_TIMEOUT.code,
							errorMessage:format(ERROR.UNSUBSCRIBE_TIMEOUT)}]);
			}
		 
			// All unsubscribes return a SUBACK.         
			this._requires_ack(wireMessage);
			this._schedule_message(wireMessage);
		};
		 
		ClientImpl.prototype.send = function (message) {
			this._trace("Client.send", message);
	
			if (!this.connected)
			   throw new Error(format(ERROR.INVALID_STATE, ["not connected"]));
			
			wireMessage = new WireMessage(MESSAGE_TYPE.PUBLISH);
			wireMessage.payloadMessage = message;
			
			if (message.qos > 0)
				this._requires_ack(wireMessage);
			else if (this.onMessageDelivered)
				this._notify_msg_sent[wireMessage] = this.onMessageDelivered(wireMessage.payloadMessage);
			this._schedule_message(wireMessage);
		};
		
		ClientImpl.prototype.disconnect = function () {
			this._trace("Client.disconnect");
	
			if (!this.socket)
				throw new Error(format(ERROR.INVALID_STATE, ["not connecting or connected"]));
			
			wireMessage = new WireMessage(MESSAGE_TYPE.DISCONNECT);
	
			// Run the disconnected call back as soon as the message has been sent,
			// in case of a failure later on in the disconnect processing.
			// as a consequence, the _disconected call back may be run several times.
			this._notify_msg_sent[wireMessage] = scope(this._disconnected, this);
	
			this._schedule_message(wireMessage);
		};
		
		ClientImpl.prototype.getTraceLog = function () {
			if ( this._traceBuffer !== null ) {
				this._trace("Client.getTraceLog", new Date());
				this._trace("Client.getTraceLog in flight messages", this._sentMessages.length);
				for (var key in this._sentMessages)
					this._trace("_sentMessages ",key, this._sentMessages[key]);
				for (var key in this._receivedMessages)
					this._trace("_receivedMessages ",key, this._receivedMessages[key]);
				
				return this._traceBuffer;
			}
		};
		
		ClientImpl.prototype.startTrace = function () {
			if ( this._traceBuffer === null ) {
				this._traceBuffer = [];
			}
			this._trace("Client.startTrace", new Date(), version);
		};
		
		ClientImpl.prototype.stopTrace = function () {
			delete this._traceBuffer;
		};
	
		ClientImpl.prototype._doConnect = function (wsurl) { 	        
			// When the socket is open, this client will send the CONNECT WireMessage using the saved parameters. 
			if (this.connectOptions.useSSL) {
			    var uriParts = wsurl.split(":");
			    uriParts[0] = "wss";
			    wsurl = uriParts.join(":");
			}
			this.connected = false;
			if (this.connectOptions.mqttVersion < 4) {
				this.socket = new WebSocket(wsurl, ["mqttv3.1"]);
			} else {
				this.socket = new WebSocket(wsurl, ["mqtt"]);
			}
			this.socket.binaryType = 'arraybuffer';
			
			this.socket.onopen = scope(this._on_socket_open, this);
			this.socket.onmessage = scope(this._on_socket_message, this);
			this.socket.onerror = scope(this._on_socket_error, this);
			this.socket.onclose = scope(this._on_socket_close, this);
			
			this.sendPinger = new Pinger(this, window, this.connectOptions.keepAliveInterval);
			this.receivePinger = new Pinger(this, window, this.connectOptions.keepAliveInterval);
			
			this._connectTimeout = new Timeout(this, window, this.connectOptions.timeout, this._disconnected,  [ERROR.CONNECT_TIMEOUT.code, format(ERROR.CONNECT_TIMEOUT)]);
		};
	
		
		// Schedule a new message to be sent over the WebSockets
		// connection. CONNECT messages cause WebSocket connection
		// to be started. All other messages are queued internally
		// until this has happened. When WS connection starts, process
		// all outstanding messages. 
		ClientImpl.prototype._schedule_message = function (message) {
			this._msg_queue.push(message);
			// Process outstanding messages in the queue if we have an  open socket, and have received CONNACK. 
			if (this.connected) {
				this._process_queue();
			}
		};
	
		ClientImpl.prototype.store = function(prefix, wireMessage) {
			var storedMessage = {type:wireMessage.type, messageIdentifier:wireMessage.messageIdentifier, version:1};
			
			switch(wireMessage.type) {
			  case MESSAGE_TYPE.PUBLISH:
				  if(wireMessage.pubRecReceived)
					  storedMessage.pubRecReceived = true;
				  
				  // Convert the payload to a hex string.
				  storedMessage.payloadMessage = {};
				  var hex = "";
				  var messageBytes = wireMessage.payloadMessage.payloadBytes;
				  for (var i=0; i<messageBytes.length; i++) {
					if (messageBytes[i] <= 0xF)
					  hex = hex+"0"+messageBytes[i].toString(16);
					else 
					  hex = hex+messageBytes[i].toString(16);
				  }
				  storedMessage.payloadMessage.payloadHex = hex;
				  
				  storedMessage.payloadMessage.qos = wireMessage.payloadMessage.qos;
				  storedMessage.payloadMessage.destinationName = wireMessage.payloadMessage.destinationName;
				  if (wireMessage.payloadMessage.duplicate) 
					  storedMessage.payloadMessage.duplicate = true;
				  if (wireMessage.payloadMessage.retained) 
					  storedMessage.payloadMessage.retained = true;	   
				  
				  // Add a sequence number to sent messages.
				  if ( prefix.indexOf("Sent:") == 0 ) {
					  if ( wireMessage.sequence === undefined )
						  wireMessage.sequence = ++this._sequence;
					  storedMessage.sequence = wireMessage.sequence;
				  }
				  break;    
				  
				default:
					throw Error(format(ERROR.INVALID_STORED_DATA, [key, storedMessage]));
			}
			localStorage.setItem(prefix+this._localKey+wireMessage.messageIdentifier, JSON.stringify(storedMessage));
		};
		
		ClientImpl.prototype.restore = function(key) {    	
			var value = localStorage.getItem(key);
			var storedMessage = JSON.parse(value);
			
			var wireMessage = new WireMessage(storedMessage.type, storedMessage);
			
			switch(storedMessage.type) {
			  case MESSAGE_TYPE.PUBLISH:
				  // Replace the payload message with a Message object.
				  var hex = storedMessage.payloadMessage.payloadHex;
				  var buffer = new ArrayBuffer((hex.length)/2);
				  var byteStream = new Uint8Array(buffer); 
				  var i = 0;
				  while (hex.length >= 2) { 
					  var x = parseInt(hex.substring(0, 2), 16);
					  hex = hex.substring(2, hex.length);
					  byteStream[i++] = x;
				  }
				  var payloadMessage = new Paho.MQTT.Message(byteStream);
				  
				  payloadMessage.qos = storedMessage.payloadMessage.qos;
				  payloadMessage.destinationName = storedMessage.payloadMessage.destinationName;
				  if (storedMessage.payloadMessage.duplicate) 
					  payloadMessage.duplicate = true;
				  if (storedMessage.payloadMessage.retained) 
					  payloadMessage.retained = true;	 
				  wireMessage.payloadMessage = payloadMessage;
				  
				  break;    
				  
				default:
				  throw Error(format(ERROR.INVALID_STORED_DATA, [key, value]));
			}
								
			if (key.indexOf("Sent:"+this._localKey) == 0) {
				wireMessage.payloadMessage.duplicate = true;
				this._sentMessages[wireMessage.messageIdentifier] = wireMessage;    		    
			} else if (key.indexOf("Received:"+this._localKey) == 0) {
				this._receivedMessages[wireMessage.messageIdentifier] = wireMessage;
			}
		};
		
		ClientImpl.prototype._process_queue = function () {
			var message = null;
			// Process messages in order they were added
			var fifo = this._msg_queue.reverse();
	
			// Send all queued messages down socket connection
			while ((message = fifo.pop())) {
				this._socket_send(message);
				// Notify listeners that message was successfully sent
				if (this._notify_msg_sent[message]) {
					this._notify_msg_sent[message]();
					delete this._notify_msg_sent[message];
				}
			}
		};
	
		/**
		 * Expect an ACK response for this message. Add message to the set of in progress
		 * messages and set an unused identifier in this message.
		 * @ignore
		 */
		ClientImpl.prototype._requires_ack = function (wireMessage) {
			var messageCount = Object.keys(this._sentMessages).length;
			if (messageCount > this.maxMessageIdentifier)
				throw Error ("Too many messages:"+messageCount);
	
			while(this._sentMessages[this._message_identifier] !== undefined) {
				this._message_identifier++;
			}
			wireMessage.messageIdentifier = this._message_identifier;
			this._sentMessages[wireMessage.messageIdentifier] = wireMessage;
			if (wireMessage.type === MESSAGE_TYPE.PUBLISH) {
				this.store("Sent:", wireMessage);
			}
			if (this._message_identifier === this.maxMessageIdentifier) {
				this._message_identifier = 1;
			}
		};
	
		/** 
		 * Called when the underlying websocket has been opened.
		 * @ignore
		 */
		ClientImpl.prototype._on_socket_open = function () {      
			// Create the CONNECT message object.
			var wireMessage = new WireMessage(MESSAGE_TYPE.CONNECT, this.connectOptions); 
			wireMessage.clientId = this.clientId;
			this._socket_send(wireMessage);
		};
	
		/** 
		 * Called when the underlying websocket has received a complete packet.
		 * @ignore
		 */
		ClientImpl.prototype._on_socket_message = function (event) {
			this._trace("Client._on_socket_message", event.data);
			// Reset the receive ping timer, we now have evidence the server is alive.
			this.receivePinger.reset();
			var messages = this._deframeMessages(event.data);
			for (var i = 0; i < messages.length; i+=1) {
			    this._handleMessage(messages[i]);
			}
		}
		
		ClientImpl.prototype._deframeMessages = function(data) {
			var byteArray = new Uint8Array(data);
		    if (this.receiveBuffer) {
		        var newData = new Uint8Array(this.receiveBuffer.length+byteArray.length);
		        newData.set(this.receiveBuffer);
		        newData.set(byteArray,this.receiveBuffer.length);
		        byteArray = newData;
		        delete this.receiveBuffer;
		    }
			try {
			    var offset = 0;
			    var messages = [];
			    while(offset < byteArray.length) {
			        var result = decodeMessage(byteArray,offset);
			        var wireMessage = result[0];
			        offset = result[1];
			        if (wireMessage !== null) {
			            messages.push(wireMessage);
			        } else {
			            break;
			        }
			    }
			    if (offset < byteArray.length) {
			    	this.receiveBuffer = byteArray.subarray(offset);
			    }
			} catch (error) {
				this._disconnected(ERROR.INTERNAL_ERROR.code , format(ERROR.INTERNAL_ERROR, [error.message,error.stack.toString()]));
				return;
			}
			return messages;
		}
		
		ClientImpl.prototype._handleMessage = function(wireMessage) {
			
			this._trace("Client._handleMessage", wireMessage);
	
			try {
				switch(wireMessage.type) {
				case MESSAGE_TYPE.CONNACK:
					this._connectTimeout.cancel();
					
					// If we have started using clean session then clear up the local state.
					if (this.connectOptions.cleanSession) {
						for (var key in this._sentMessages) {	    		
							var sentMessage = this._sentMessages[key];
							localStorage.removeItem("Sent:"+this._localKey+sentMessage.messageIdentifier);
						}
						this._sentMessages = {};
	
						for (var key in this._receivedMessages) {
							var receivedMessage = this._receivedMessages[key];
							localStorage.removeItem("Received:"+this._localKey+receivedMessage.messageIdentifier);
						}
						this._receivedMessages = {};
					}
					// Client connected and ready for business.
					if (wireMessage.returnCode === 0) {
						this.connected = true;
						// Jump to the end of the list of uris and stop looking for a good host.
						if (this.connectOptions.uris)
							this.hostIndex = this.connectOptions.uris.length;
					} else {
						this._disconnected(ERROR.CONNACK_RETURNCODE.code , format(ERROR.CONNACK_RETURNCODE, [wireMessage.returnCode, CONNACK_RC[wireMessage.returnCode]]));
						break;
					}
					
					// Resend messages.
					var sequencedMessages = new Array();
					for (var msgId in this._sentMessages) {
						if (this._sentMessages.hasOwnProperty(msgId))
							sequencedMessages.push(this._sentMessages[msgId]);
					}
			  
					// Sort sentMessages into the original sent order.
					var sequencedMessages = sequencedMessages.sort(function(a,b) {return a.sequence - b.sequence;} );
					for (var i=0, len=sequencedMessages.length; i<len; i++) {
						var sentMessage = sequencedMessages[i];
						if (sentMessage.type == MESSAGE_TYPE.PUBLISH && sentMessage.pubRecReceived) {
							var pubRelMessage = new WireMessage(MESSAGE_TYPE.PUBREL, {messageIdentifier:sentMessage.messageIdentifier});
							this._schedule_message(pubRelMessage);
						} else {
							this._schedule_message(sentMessage);
						};
					}
	
					// Execute the connectOptions.onSuccess callback if there is one.
					if (this.connectOptions.onSuccess) {
						this.connectOptions.onSuccess({invocationContext:this.connectOptions.invocationContext});
					}
	
					// Process all queued messages now that the connection is established. 
					this._process_queue();
					break;
			
				case MESSAGE_TYPE.PUBLISH:
					this._receivePublish(wireMessage);
					break;
	
				case MESSAGE_TYPE.PUBACK:
					var sentMessage = this._sentMessages[wireMessage.messageIdentifier];
					 // If this is a re flow of a PUBACK after we have restarted receivedMessage will not exist.
					if (sentMessage) {
						delete this._sentMessages[wireMessage.messageIdentifier];
						localStorage.removeItem("Sent:"+this._localKey+wireMessage.messageIdentifier);
						if (this.onMessageDelivered)
							this.onMessageDelivered(sentMessage.payloadMessage);
					}
					break;
				
				case MESSAGE_TYPE.PUBREC:
					var sentMessage = this._sentMessages[wireMessage.messageIdentifier];
					// If this is a re flow of a PUBREC after we have restarted receivedMessage will not exist.
					if (sentMessage) {
						sentMessage.pubRecReceived = true;
						var pubRelMessage = new WireMessage(MESSAGE_TYPE.PUBREL, {messageIdentifier:wireMessage.messageIdentifier});
						this.store("Sent:", sentMessage);
						this._schedule_message(pubRelMessage);
					}
					break;
									
				case MESSAGE_TYPE.PUBREL:
					var receivedMessage = this._receivedMessages[wireMessage.messageIdentifier];
					localStorage.removeItem("Received:"+this._localKey+wireMessage.messageIdentifier);
					// If this is a re flow of a PUBREL after we have restarted receivedMessage will not exist.
					if (receivedMessage) {
						this._receiveMessage(receivedMessage);
						delete this._receivedMessages[wireMessage.messageIdentifier];
					}
					// Always flow PubComp, we may have previously flowed PubComp but the server lost it and restarted.
					var pubCompMessage = new WireMessage(MESSAGE_TYPE.PUBCOMP, {messageIdentifier:wireMessage.messageIdentifier});
					this._schedule_message(pubCompMessage);                    
					break;
	
				case MESSAGE_TYPE.PUBCOMP: 
					var sentMessage = this._sentMessages[wireMessage.messageIdentifier];
					delete this._sentMessages[wireMessage.messageIdentifier];
					localStorage.removeItem("Sent:"+this._localKey+wireMessage.messageIdentifier);
					if (this.onMessageDelivered)
						this.onMessageDelivered(sentMessage.payloadMessage);
					break;
					
				case MESSAGE_TYPE.SUBACK:
					var sentMessage = this._sentMessages[wireMessage.messageIdentifier];
					if (sentMessage) {
						if(sentMessage.timeOut)
							sentMessage.timeOut.cancel();
						// This will need to be fixed when we add multiple topic support
	          			if (wireMessage.returnCode[0] === 0x80) {
							if (sentMessage.onFailure) {
								sentMessage.onFailure(wireMessage.returnCode);
							} 
						} else if (sentMessage.onSuccess) {
							sentMessage.onSuccess(wireMessage.returnCode);
						}
						delete this._sentMessages[wireMessage.messageIdentifier];
					}
					break;
					
				case MESSAGE_TYPE.UNSUBACK:
					var sentMessage = this._sentMessages[wireMessage.messageIdentifier];
					if (sentMessage) { 
						if (sentMessage.timeOut)
							sentMessage.timeOut.cancel();
						if (sentMessage.callback) {
							sentMessage.callback();
						}
						delete this._sentMessages[wireMessage.messageIdentifier];
					}
	
					break;
					
				case MESSAGE_TYPE.PINGRESP:
					/* The sendPinger or receivePinger may have sent a ping, the receivePinger has already been reset. */
					this.sendPinger.reset();
					break;
					
				case MESSAGE_TYPE.DISCONNECT:
					// Clients do not expect to receive disconnect packets.
					this._disconnected(ERROR.INVALID_MQTT_MESSAGE_TYPE.code , format(ERROR.INVALID_MQTT_MESSAGE_TYPE, [wireMessage.type]));
					break;
	
				default:
					this._disconnected(ERROR.INVALID_MQTT_MESSAGE_TYPE.code , format(ERROR.INVALID_MQTT_MESSAGE_TYPE, [wireMessage.type]));
				};
			} catch (error) {
				this._disconnected(ERROR.INTERNAL_ERROR.code , format(ERROR.INTERNAL_ERROR, [error.message,error.stack.toString()]));
				return;
			}
		};
		
		/** @ignore */
		ClientImpl.prototype._on_socket_error = function (error) {
			this._disconnected(ERROR.SOCKET_ERROR.code , format(ERROR.SOCKET_ERROR, [error.data]));
		};
	
		/** @ignore */
		ClientImpl.prototype._on_socket_close = function () {
			this._disconnected(ERROR.SOCKET_CLOSE.code , format(ERROR.SOCKET_CLOSE));
		};
	
		/** @ignore */
		ClientImpl.prototype._socket_send = function (wireMessage) {
			
			if (wireMessage.type == 1) {
				var wireMessageMasked = this._traceMask(wireMessage, "password"); 
				this._trace("Client._socket_send", wireMessageMasked);
			}
			else this._trace("Client._socket_send", wireMessage);
			
			this.socket.send(wireMessage.encode());
			/* We have proved to the server we are alive. */
			this.sendPinger.reset();
		};
		
		/** @ignore */
		ClientImpl.prototype._receivePublish = function (wireMessage) {
			switch(wireMessage.payloadMessage.qos) {
				case "undefined":
				case 0:
					this._receiveMessage(wireMessage);
					break;
	
				case 1:
					var pubAckMessage = new WireMessage(MESSAGE_TYPE.PUBACK, {messageIdentifier:wireMessage.messageIdentifier});
					this._schedule_message(pubAckMessage);
					this._receiveMessage(wireMessage);
					break;
	
				case 2:
					this._receivedMessages[wireMessage.messageIdentifier] = wireMessage;
					this.store("Received:", wireMessage);
					var pubRecMessage = new WireMessage(MESSAGE_TYPE.PUBREC, {messageIdentifier:wireMessage.messageIdentifier});
					this._schedule_message(pubRecMessage);
	
					break;
	
				default:
					throw Error("Invaild qos="+wireMmessage.payloadMessage.qos);
			};
		};
	
		/** @ignore */
		ClientImpl.prototype._receiveMessage = function (wireMessage) {
			if (this.onMessageArrived) {
				this.onMessageArrived(wireMessage.payloadMessage);
			}
		};
	
		/**
		 * Client has disconnected either at its own request or because the server
		 * or network disconnected it. Remove all non-durable state.
		 * @param {errorCode} [number] the error number.
		 * @param {errorText} [string] the error text.
		 * @ignore
		 */
		ClientImpl.prototype._disconnected = function (errorCode, errorText) {
			this._trace("Client._disconnected", errorCode, errorText);
			
			this.sendPinger.cancel();
			this.receivePinger.cancel();
			if (this._connectTimeout)
				this._connectTimeout.cancel();
			// Clear message buffers.
			this._msg_queue = [];
			this._notify_msg_sent = {};
		   
			if (this.socket) {
				// Cancel all socket callbacks so that they cannot be driven again by this socket.
				this.socket.onopen = null;
				this.socket.onmessage = null;
				this.socket.onerror = null;
				this.socket.onclose = null;
				if (this.socket.readyState === 1)
					this.socket.close();
				delete this.socket;           
			}
			
			if (this.connectOptions.uris && this.hostIndex < this.connectOptions.uris.length-1) {
				// Try the next host.
				this.hostIndex++;
				this._doConnect(this.connectOptions.uris[this.hostIndex]);
			
			} else {
			
				if (errorCode === undefined) {
					errorCode = ERROR.OK.code;
					errorText = format(ERROR.OK);
				}
				
				// Run any application callbacks last as they may attempt to reconnect and hence create a new socket.
				if (this.connected) {
					this.connected = false;
					// Execute the connectionLostCallback if there is one, and we were connected.       
					if (this.onConnectionLost)
						this.onConnectionLost({errorCode:errorCode, errorMessage:errorText});      	
				} else {
					// Otherwise we never had a connection, so indicate that the connect has failed.
					if (this.connectOptions.mqttVersion === 4 && this.connectOptions.mqttVersionExplicit === false) {
						this._trace("Failed to connect V4, dropping back to V3")
						this.connectOptions.mqttVersion = 3;
						if (this.connectOptions.uris) {
							this.hostIndex = 0;
							this._doConnect(this.connectOptions.uris[0]);  
						} else {
							this._doConnect(this.uri);
						}	
					} else if(this.connectOptions.onFailure) {
						this.connectOptions.onFailure({invocationContext:this.connectOptions.invocationContext, errorCode:errorCode, errorMessage:errorText});
					}
				}
			}
		};
	
		/** @ignore */
		ClientImpl.prototype._trace = function () {
			// Pass trace message back to client's callback function
			if (this.traceFunction) {
				for (var i in arguments)
				{	
					if (typeof arguments[i] !== "undefined")
						arguments[i] = JSON.stringify(arguments[i]);
				}
				var record = Array.prototype.slice.call(arguments).join("");
				this.traceFunction ({severity: "Debug", message: record	});
			}
	
			//buffer style trace
			if ( this._traceBuffer !== null ) {  
				for (var i = 0, max = arguments.length; i < max; i++) {
					if ( this._traceBuffer.length == this._MAX_TRACE_ENTRIES ) {    
						this._traceBuffer.shift();              
					}
					if (i === 0) this._traceBuffer.push(arguments[i]);
					else if (typeof arguments[i] === "undefined" ) this._traceBuffer.push(arguments[i]);
					else this._traceBuffer.push("  "+JSON.stringify(arguments[i]));
			   };
			};
		};
		
		/** @ignore */
		ClientImpl.prototype._traceMask = function (traceObject, masked) {
			var traceObjectMasked = {};
			for (var attr in traceObject) {
				if (traceObject.hasOwnProperty(attr)) {
					if (attr == masked) 
						traceObjectMasked[attr] = "******";
					else
						traceObjectMasked[attr] = traceObject[attr];
				} 
			}
			return traceObjectMasked;
		};
	
		// ------------------------------------------------------------------------
		// Public Programming interface.
		// ------------------------------------------------------------------------
		
		/** 
		 * The JavaScript application communicates to the server using a {@link Paho.MQTT.Client} object. 
		 * <p>
		 * Most applications will create just one Client object and then call its connect() method,
		 * however applications can create more than one Client object if they wish. 
		 * In this case the combination of host, port and clientId attributes must be different for each Client object.
		 * <p>
		 * The send, subscribe and unsubscribe methods are implemented as asynchronous JavaScript methods 
		 * (even though the underlying protocol exchange might be synchronous in nature). 
		 * This means they signal their completion by calling back to the application, 
		 * via Success or Failure callback functions provided by the application on the method in question. 
		 * Such callbacks are called at most once per method invocation and do not persist beyond the lifetime 
		 * of the script that made the invocation.
		 * <p>
		 * In contrast there are some callback functions, most notably <i>onMessageArrived</i>, 
		 * that are defined on the {@link Paho.MQTT.Client} object.  
		 * These may get called multiple times, and aren't directly related to specific method invocations made by the client. 
		 *
		 * @name Paho.MQTT.Client    
		 * 
		 * @constructor
		 *  
		 * @param {string} host - the address of the messaging server, as a fully qualified WebSocket URI, as a DNS name or dotted decimal IP address.
		 * @param {number} port - the port number to connect to - only required if host is not a URI
		 * @param {string} path - the path on the host to connect to - only used if host is not a URI. Default: '/mqtt'.
		 * @param {string} clientId - the Messaging client identifier, between 1 and 23 characters in length.
		 * 
		 * @property {string} host - <i>read only</i> the server's DNS hostname or dotted decimal IP address.
		 * @property {number} port - <i>read only</i> the server's port.
		 * @property {string} path - <i>read only</i> the server's path.
		 * @property {string} clientId - <i>read only</i> used when connecting to the server.
		 * @property {function} onConnectionLost - called when a connection has been lost. 
		 *                            after a connect() method has succeeded.
		 *                            Establish the call back used when a connection has been lost. The connection may be
		 *                            lost because the client initiates a disconnect or because the server or network 
		 *                            cause the client to be disconnected. The disconnect call back may be called without 
		 *                            the connectionComplete call back being invoked if, for example the client fails to 
		 *                            connect.
		 *                            A single response object parameter is passed to the onConnectionLost callback containing the following fields:
		 *                            <ol>   
		 *                            <li>errorCode
		 *                            <li>errorMessage       
		 *                            </ol>
		 * @property {function} onMessageDelivered called when a message has been delivered. 
		 *                            All processing that this Client will ever do has been completed. So, for example,
		 *                            in the case of a Qos=2 message sent by this client, the PubComp flow has been received from the server
		 *                            and the message has been removed from persistent storage before this callback is invoked. 
		 *                            Parameters passed to the onMessageDelivered callback are:
		 *                            <ol>   
		 *                            <li>{@link Paho.MQTT.Message} that was delivered.
		 *                            </ol>    
		 * @property {function} onMessageArrived called when a message has arrived in this Paho.MQTT.client. 
		 *                            Parameters passed to the onMessageArrived callback are:
		 *                            <ol>   
		 *                            <li>{@link Paho.MQTT.Message} that has arrived.
		 *                            </ol>    
		 */
		var Client = function (host, port, path, clientId) {
		    
		    var uri;
		    
			if (typeof host !== "string")
				throw new Error(format(ERROR.INVALID_TYPE, [typeof host, "host"]));
		    
		    if (arguments.length == 2) {
		        // host: must be full ws:// uri
		        // port: clientId
		        clientId = port;
		        uri = host;
		        var match = uri.match(/^(wss?):\/\/((\[(.+)\])|([^\/]+?))(:(\d+))?(\/.*)$/);
		        if (match) {
		            host = match[4]||match[2];
		            port = parseInt(match[7]);
		            path = match[8];
		        } else {
		            throw new Error(format(ERROR.INVALID_ARGUMENT,[host,"host"]));
		        }
		    } else {
		        if (arguments.length == 3) {
					clientId = path;
					path = "/mqtt";
				}
				if (typeof port !== "number" || port < 0)
					throw new Error(format(ERROR.INVALID_TYPE, [typeof port, "port"]));
				if (typeof path !== "string")
					throw new Error(format(ERROR.INVALID_TYPE, [typeof path, "path"]));
				
				var ipv6AddSBracket = (host.indexOf(":") != -1 && host.slice(0,1) != "[" && host.slice(-1) != "]");
				uri = "ws://"+(ipv6AddSBracket?"["+host+"]":host)+":"+port+path;
			}
	
			var clientIdLength = 0;
			for (var i = 0; i<clientId.length; i++) {
				var charCode = clientId.charCodeAt(i);                   
				if (0xD800 <= charCode && charCode <= 0xDBFF)  {    			
					 i++; // Surrogate pair.
				}   		   
				clientIdLength++;
			}     	   	
			if (typeof clientId !== "string" || clientIdLength > 65535)
				throw new Error(format(ERROR.INVALID_ARGUMENT, [clientId, "clientId"])); 
			
			var client = new ClientImpl(uri, host, port, path, clientId);
			this._getHost =  function() { return host; };
			this._setHost = function() { throw new Error(format(ERROR.UNSUPPORTED_OPERATION)); };
				
			this._getPort = function() { return port; };
			this._setPort = function() { throw new Error(format(ERROR.UNSUPPORTED_OPERATION)); };
	
			this._getPath = function() { return path; };
			this._setPath = function() { throw new Error(format(ERROR.UNSUPPORTED_OPERATION)); };
	
			this._getURI = function() { return uri; };
			this._setURI = function() { throw new Error(format(ERROR.UNSUPPORTED_OPERATION)); };
			
			this._getClientId = function() { return client.clientId; };
			this._setClientId = function() { throw new Error(format(ERROR.UNSUPPORTED_OPERATION)); };
			
			this._getOnConnectionLost = function() { return client.onConnectionLost; };
			this._setOnConnectionLost = function(newOnConnectionLost) { 
				if (typeof newOnConnectionLost === "function")
					client.onConnectionLost = newOnConnectionLost;
				else 
					throw new Error(format(ERROR.INVALID_TYPE, [typeof newOnConnectionLost, "onConnectionLost"]));
			};
	
			this._getOnMessageDelivered = function() { return client.onMessageDelivered; };
			this._setOnMessageDelivered = function(newOnMessageDelivered) { 
				if (typeof newOnMessageDelivered === "function")
					client.onMessageDelivered = newOnMessageDelivered;
				else 
					throw new Error(format(ERROR.INVALID_TYPE, [typeof newOnMessageDelivered, "onMessageDelivered"]));
			};
		   
			this._getOnMessageArrived = function() { return client.onMessageArrived; };
			this._setOnMessageArrived = function(newOnMessageArrived) { 
				if (typeof newOnMessageArrived === "function")
					client.onMessageArrived = newOnMessageArrived;
				else 
					throw new Error(format(ERROR.INVALID_TYPE, [typeof newOnMessageArrived, "onMessageArrived"]));
			};
	
			this._getTrace = function() { return client.traceFunction; };
			this._setTrace = function(trace) {
				if(typeof trace === "function"){
					client.traceFunction = trace;
				}else{
					throw new Error(format(ERROR.INVALID_TYPE, [typeof trace, "onTrace"]));
				}
			};
			
			/** 
			 * Connect this Messaging client to its server. 
			 * 
			 * @name Paho.MQTT.Client#connect
			 * @function
			 * @param {Object} connectOptions - attributes used with the connection. 
			 * @param {number} connectOptions.timeout - If the connect has not succeeded within this 
			 *                    number of seconds, it is deemed to have failed.
			 *                    The default is 30 seconds.
			 * @param {string} connectOptions.userName - Authentication username for this connection.
			 * @param {string} connectOptions.password - Authentication password for this connection.
			 * @param {Paho.MQTT.Message} connectOptions.willMessage - sent by the server when the client
			 *                    disconnects abnormally.
			 * @param {Number} connectOptions.keepAliveInterval - the server disconnects this client if
			 *                    there is no activity for this number of seconds.
			 *                    The default value of 60 seconds is assumed if not set.
			 * @param {boolean} connectOptions.cleanSession - if true(default) the client and server 
			 *                    persistent state is deleted on successful connect.
			 * @param {boolean} connectOptions.useSSL - if present and true, use an SSL Websocket connection.
			 * @param {object} connectOptions.invocationContext - passed to the onSuccess callback or onFailure callback.
			 * @param {function} connectOptions.onSuccess - called when the connect acknowledgement 
			 *                    has been received from the server.
			 * A single response object parameter is passed to the onSuccess callback containing the following fields:
			 * <ol>
			 * <li>invocationContext as passed in to the onSuccess method in the connectOptions.       
			 * </ol>
			 * @config {function} [onFailure] called when the connect request has failed or timed out.
			 * A single response object parameter is passed to the onFailure callback containing the following fields:
			 * <ol>
			 * <li>invocationContext as passed in to the onFailure method in the connectOptions.       
			 * <li>errorCode a number indicating the nature of the error.
			 * <li>errorMessage text describing the error.      
			 * </ol>
			 * @config {Array} [hosts] If present this contains either a set of hostnames or fully qualified
			 * WebSocket URIs (ws://example.com:1883/mqtt), that are tried in order in place 
			 * of the host and port paramater on the construtor. The hosts are tried one at at time in order until
			 * one of then succeeds.
			 * @config {Array} [ports] If present the set of ports matching the hosts. If hosts contains URIs, this property
			 * is not used.
			 * @throws {InvalidState} if the client is not in disconnected state. The client must have received connectionLost
			 * or disconnected before calling connect for a second or subsequent time.
			 */
			this.connect = function (connectOptions) {
				connectOptions = connectOptions || {} ;
				validate(connectOptions,  {timeout:"number",
										   userName:"string", 
										   password:"string", 
										   willMessage:"object", 
										   keepAliveInterval:"number", 
										   cleanSession:"boolean", 
										   useSSL:"boolean",
										   invocationContext:"object", 
										   onSuccess:"function", 
										   onFailure:"function",
										   hosts:"object",
										   ports:"object",
										   mqttVersion:"number"});
				
				// If no keep alive interval is set, assume 60 seconds.
				if (connectOptions.keepAliveInterval === undefined)
					connectOptions.keepAliveInterval = 60;
	
				if (connectOptions.mqttVersion > 4 || connectOptions.mqttVersion < 3) {
					throw new Error(format(ERROR.INVALID_ARGUMENT, [connectOptions.mqttVersion, "connectOptions.mqttVersion"]));
				}
	
				if (connectOptions.mqttVersion === undefined) {
					connectOptions.mqttVersionExplicit = false;
					connectOptions.mqttVersion = 4;
				} else {
					connectOptions.mqttVersionExplicit = true;
				}
	
				//Check that if password is set, so is username
				if (connectOptions.password === undefined && connectOptions.userName !== undefined)
					throw new Error(format(ERROR.INVALID_ARGUMENT, [connectOptions.password, "connectOptions.password"]))
	
				if (connectOptions.willMessage) {
					if (!(connectOptions.willMessage instanceof Message))
						throw new Error(format(ERROR.INVALID_TYPE, [connectOptions.willMessage, "connectOptions.willMessage"]));
					// The will message must have a payload that can be represented as a string.
					// Cause the willMessage to throw an exception if this is not the case.
					connectOptions.willMessage.stringPayload;
					
					if (typeof connectOptions.willMessage.destinationName === "undefined")
						throw new Error(format(ERROR.INVALID_TYPE, [typeof connectOptions.willMessage.destinationName, "connectOptions.willMessage.destinationName"]));
				}
				if (typeof connectOptions.cleanSession === "undefined")
					connectOptions.cleanSession = true;
				if (connectOptions.hosts) {
				    
					if (!(connectOptions.hosts instanceof Array) )
						throw new Error(format(ERROR.INVALID_ARGUMENT, [connectOptions.hosts, "connectOptions.hosts"]));
					if (connectOptions.hosts.length <1 )
						throw new Error(format(ERROR.INVALID_ARGUMENT, [connectOptions.hosts, "connectOptions.hosts"]));
					
					var usingURIs = false;
					for (var i = 0; i<connectOptions.hosts.length; i++) {
						if (typeof connectOptions.hosts[i] !== "string")
							throw new Error(format(ERROR.INVALID_TYPE, [typeof connectOptions.hosts[i], "connectOptions.hosts["+i+"]"]));
						if (/^(wss?):\/\/((\[(.+)\])|([^\/]+?))(:(\d+))?(\/.*)$/.test(connectOptions.hosts[i])) {
							if (i == 0) {
								usingURIs = true;
							} else if (!usingURIs) {
								throw new Error(format(ERROR.INVALID_ARGUMENT, [connectOptions.hosts[i], "connectOptions.hosts["+i+"]"]));
							}
						} else if (usingURIs) {
							throw new Error(format(ERROR.INVALID_ARGUMENT, [connectOptions.hosts[i], "connectOptions.hosts["+i+"]"]));
						}
					}
					
					if (!usingURIs) {
						if (!connectOptions.ports)
							throw new Error(format(ERROR.INVALID_ARGUMENT, [connectOptions.ports, "connectOptions.ports"]));
						if (!(connectOptions.ports instanceof Array) )
							throw new Error(format(ERROR.INVALID_ARGUMENT, [connectOptions.ports, "connectOptions.ports"]));
						if (connectOptions.hosts.length != connectOptions.ports.length)
							throw new Error(format(ERROR.INVALID_ARGUMENT, [connectOptions.ports, "connectOptions.ports"]));
						
						connectOptions.uris = [];
						
						for (var i = 0; i<connectOptions.hosts.length; i++) {
							if (typeof connectOptions.ports[i] !== "number" || connectOptions.ports[i] < 0)
								throw new Error(format(ERROR.INVALID_TYPE, [typeof connectOptions.ports[i], "connectOptions.ports["+i+"]"]));
							var host = connectOptions.hosts[i];
							var port = connectOptions.ports[i];
							
							var ipv6 = (host.indexOf(":") != -1);
							uri = "ws://"+(ipv6?"["+host+"]":host)+":"+port+path;
							connectOptions.uris.push(uri);
						}
					} else {
						connectOptions.uris = connectOptions.hosts;
					}
				}
				
				client.connect(connectOptions);
			};
		 
			/** 
			 * Subscribe for messages, request receipt of a copy of messages sent to the destinations described by the filter.
			 * 
			 * @name Paho.MQTT.Client#subscribe
			 * @function
			 * @param {string} filter describing the destinations to receive messages from.
			 * <br>
			 * @param {object} subscribeOptions - used to control the subscription
			 *
			 * @param {number} subscribeOptions.qos - the maiximum qos of any publications sent 
			 *                                  as a result of making this subscription.
			 * @param {object} subscribeOptions.invocationContext - passed to the onSuccess callback 
			 *                                  or onFailure callback.
			 * @param {function} subscribeOptions.onSuccess - called when the subscribe acknowledgement
			 *                                  has been received from the server.
			 *                                  A single response object parameter is passed to the onSuccess callback containing the following fields:
			 *                                  <ol>
			 *                                  <li>invocationContext if set in the subscribeOptions.       
			 *                                  </ol>
			 * @param {function} subscribeOptions.onFailure - called when the subscribe request has failed or timed out.
			 *                                  A single response object parameter is passed to the onFailure callback containing the following fields:
			 *                                  <ol>
			 *                                  <li>invocationContext - if set in the subscribeOptions.       
			 *                                  <li>errorCode - a number indicating the nature of the error.
			 *                                  <li>errorMessage - text describing the error.      
			 *                                  </ol>
			 * @param {number} subscribeOptions.timeout - which, if present, determines the number of
			 *                                  seconds after which the onFailure calback is called.
			 *                                  The presence of a timeout does not prevent the onSuccess
			 *                                  callback from being called when the subscribe completes.         
			 * @throws {InvalidState} if the client is not in connected state.
			 */
			this.subscribe = function (filter, subscribeOptions) {
				if (typeof filter !== "string")
					throw new Error("Invalid argument:"+filter);
				subscribeOptions = subscribeOptions || {} ;
				validate(subscribeOptions,  {qos:"number", 
											 invocationContext:"object", 
											 onSuccess:"function", 
											 onFailure:"function",
											 timeout:"number"
											});
				if (subscribeOptions.timeout && !subscribeOptions.onFailure)
					throw new Error("subscribeOptions.timeout specified with no onFailure callback.");
				if (typeof subscribeOptions.qos !== "undefined" 
					&& !(subscribeOptions.qos === 0 || subscribeOptions.qos === 1 || subscribeOptions.qos === 2 ))
					throw new Error(format(ERROR.INVALID_ARGUMENT, [subscribeOptions.qos, "subscribeOptions.qos"]));
				client.subscribe(filter, subscribeOptions);
			};
	
			/**
			 * Unsubscribe for messages, stop receiving messages sent to destinations described by the filter.
			 * 
			 * @name Paho.MQTT.Client#unsubscribe
			 * @function
			 * @param {string} filter - describing the destinations to receive messages from.
			 * @param {object} unsubscribeOptions - used to control the subscription
			 * @param {object} unsubscribeOptions.invocationContext - passed to the onSuccess callback 
			                                      or onFailure callback.
			 * @param {function} unsubscribeOptions.onSuccess - called when the unsubscribe acknowledgement has been received from the server.
			 *                                    A single response object parameter is passed to the 
			 *                                    onSuccess callback containing the following fields:
			 *                                    <ol>
			 *                                    <li>invocationContext - if set in the unsubscribeOptions.     
			 *                                    </ol>
			 * @param {function} unsubscribeOptions.onFailure called when the unsubscribe request has failed or timed out.
			 *                                    A single response object parameter is passed to the onFailure callback containing the following fields:
			 *                                    <ol>
			 *                                    <li>invocationContext - if set in the unsubscribeOptions.       
			 *                                    <li>errorCode - a number indicating the nature of the error.
			 *                                    <li>errorMessage - text describing the error.      
			 *                                    </ol>
			 * @param {number} unsubscribeOptions.timeout - which, if present, determines the number of seconds
			 *                                    after which the onFailure callback is called. The presence of
			 *                                    a timeout does not prevent the onSuccess callback from being
			 *                                    called when the unsubscribe completes
			 * @throws {InvalidState} if the client is not in connected state.
			 */
			this.unsubscribe = function (filter, unsubscribeOptions) {
				if (typeof filter !== "string")
					throw new Error("Invalid argument:"+filter);
				unsubscribeOptions = unsubscribeOptions || {} ;
				validate(unsubscribeOptions,  {invocationContext:"object", 
											   onSuccess:"function", 
											   onFailure:"function",
											   timeout:"number"
											  });
				if (unsubscribeOptions.timeout && !unsubscribeOptions.onFailure)
					throw new Error("unsubscribeOptions.timeout specified with no onFailure callback.");
				client.unsubscribe(filter, unsubscribeOptions);
			};
	
			/**
			 * Send a message to the consumers of the destination in the Message.
			 * 
			 * @name Paho.MQTT.Client#send
			 * @function 
			 * @param {string|Paho.MQTT.Message} topic - <b>mandatory</b> The name of the destination to which the message is to be sent. 
			 * 					   - If it is the only parameter, used as Paho.MQTT.Message object.
			 * @param {String|ArrayBuffer} payload - The message data to be sent. 
			 * @param {number} qos The Quality of Service used to deliver the message.
			 * 		<dl>
			 * 			<dt>0 Best effort (default).
			 *     			<dt>1 At least once.
			 *     			<dt>2 Exactly once.     
			 * 		</dl>
			 * @param {Boolean} retained If true, the message is to be retained by the server and delivered 
			 *                     to both current and future subscriptions.
			 *                     If false the server only delivers the message to current subscribers, this is the default for new Messages. 
			 *                     A received message has the retained boolean set to true if the message was published 
			 *                     with the retained boolean set to true
			 *                     and the subscrption was made after the message has been published. 
			 * @throws {InvalidState} if the client is not connected.
			 */   
			this.send = function (topic,payload,qos,retained) {   
				var message ;  
				
				if(arguments.length == 0){
					throw new Error("Invalid argument."+"length");
	
				}else if(arguments.length == 1) {
	
					if (!(topic instanceof Message) && (typeof topic !== "string"))
						throw new Error("Invalid argument:"+ typeof topic);
	
					message = topic;
					if (typeof message.destinationName === "undefined")
						throw new Error(format(ERROR.INVALID_ARGUMENT,[message.destinationName,"Message.destinationName"]));
					client.send(message); 
	
				}else {
					//parameter checking in Message object 
					message = new Message(payload);
					message.destinationName = topic;
					if(arguments.length >= 3)
						message.qos = qos;
					if(arguments.length >= 4)
						message.retained = retained;
					client.send(message); 
				}
			};
			
			/** 
			 * Normal disconnect of this Messaging client from its server.
			 * 
			 * @name Paho.MQTT.Client#disconnect
			 * @function
			 * @throws {InvalidState} if the client is already disconnected.     
			 */
			this.disconnect = function () {
				client.disconnect();
			};
			
			/** 
			 * Get the contents of the trace log.
			 * 
			 * @name Paho.MQTT.Client#getTraceLog
			 * @function
			 * @return {Object[]} tracebuffer containing the time ordered trace records.
			 */
			this.getTraceLog = function () {
				return client.getTraceLog();
			}
			
			/** 
			 * Start tracing.
			 * 
			 * @name Paho.MQTT.Client#startTrace
			 * @function
			 */
			this.startTrace = function () {
				client.startTrace();
			};
			
			/** 
			 * Stop tracing.
			 * 
			 * @name Paho.MQTT.Client#stopTrace
			 * @function
			 */
			this.stopTrace = function () {
				client.stopTrace();
			};
	
			this.isConnected = function() {
				return client.connected;
			};
		};
	
		Client.prototype = {
			get host() { return this._getHost(); },
			set host(newHost) { this._setHost(newHost); },
				
			get port() { return this._getPort(); },
			set port(newPort) { this._setPort(newPort); },
	
			get path() { return this._getPath(); },
			set path(newPath) { this._setPath(newPath); },
				
			get clientId() { return this._getClientId(); },
			set clientId(newClientId) { this._setClientId(newClientId); },
	
			get onConnectionLost() { return this._getOnConnectionLost(); },
			set onConnectionLost(newOnConnectionLost) { this._setOnConnectionLost(newOnConnectionLost); },
	
			get onMessageDelivered() { return this._getOnMessageDelivered(); },
			set onMessageDelivered(newOnMessageDelivered) { this._setOnMessageDelivered(newOnMessageDelivered); },
			
			get onMessageArrived() { return this._getOnMessageArrived(); },
			set onMessageArrived(newOnMessageArrived) { this._setOnMessageArrived(newOnMessageArrived); },
	
			get trace() { return this._getTrace(); },
			set trace(newTraceFunction) { this._setTrace(newTraceFunction); }	
	
		};
		
		/** 
		 * An application message, sent or received.
		 * <p>
		 * All attributes may be null, which implies the default values.
		 * 
		 * @name Paho.MQTT.Message
		 * @constructor
		 * @param {String|ArrayBuffer} payload The message data to be sent.
		 * <p>
		 * @property {string} payloadString <i>read only</i> The payload as a string if the payload consists of valid UTF-8 characters.
		 * @property {ArrayBuffer} payloadBytes <i>read only</i> The payload as an ArrayBuffer.
		 * <p>
		 * @property {string} destinationName <b>mandatory</b> The name of the destination to which the message is to be sent
		 *                    (for messages about to be sent) or the name of the destination from which the message has been received.
		 *                    (for messages received by the onMessage function).
		 * <p>
		 * @property {number} qos The Quality of Service used to deliver the message.
		 * <dl>
		 *     <dt>0 Best effort (default).
		 *     <dt>1 At least once.
		 *     <dt>2 Exactly once.     
		 * </dl>
		 * <p>
		 * @property {Boolean} retained If true, the message is to be retained by the server and delivered 
		 *                     to both current and future subscriptions.
		 *                     If false the server only delivers the message to current subscribers, this is the default for new Messages. 
		 *                     A received message has the retained boolean set to true if the message was published 
		 *                     with the retained boolean set to true
		 *                     and the subscrption was made after the message has been published. 
		 * <p>
		 * @property {Boolean} duplicate <i>read only</i> If true, this message might be a duplicate of one which has already been received. 
		 *                     This is only set on messages received from the server.
		 *                     
		 */
		var Message = function (newPayload) {  
			var payload;
			if (   typeof newPayload === "string" 
				|| newPayload instanceof ArrayBuffer
				|| newPayload instanceof Int8Array
				|| newPayload instanceof Uint8Array
				|| newPayload instanceof Int16Array
				|| newPayload instanceof Uint16Array
				|| newPayload instanceof Int32Array
				|| newPayload instanceof Uint32Array
				|| newPayload instanceof Float32Array
				|| newPayload instanceof Float64Array
			   ) {
				payload = newPayload;
			} else {
				throw (format(ERROR.INVALID_ARGUMENT, [newPayload, "newPayload"]));
			}
	
			this._getPayloadString = function () {
				if (typeof payload === "string")
					return payload;
				else
					return parseUTF8(payload, 0, payload.length); 
			};
	
			this._getPayloadBytes = function() {
				if (typeof payload === "string") {
					var buffer = new ArrayBuffer(UTF8Length(payload));
					var byteStream = new Uint8Array(buffer); 
					stringToUTF8(payload, byteStream, 0);
	
					return byteStream;
				} else {
					return payload;
				};
			};
	
			var destinationName = undefined;
			this._getDestinationName = function() { return destinationName; };
			this._setDestinationName = function(newDestinationName) { 
				if (typeof newDestinationName === "string")
					destinationName = newDestinationName;
				else 
					throw new Error(format(ERROR.INVALID_ARGUMENT, [newDestinationName, "newDestinationName"]));
			};
					
			var qos = 0;
			this._getQos = function() { return qos; };
			this._setQos = function(newQos) { 
				if (newQos === 0 || newQos === 1 || newQos === 2 )
					qos = newQos;
				else 
					throw new Error("Invalid argument:"+newQos);
			};
	
			var retained = false;
			this._getRetained = function() { return retained; };
			this._setRetained = function(newRetained) { 
				if (typeof newRetained === "boolean")
					retained = newRetained;
				else 
					throw new Error(format(ERROR.INVALID_ARGUMENT, [newRetained, "newRetained"]));
			};
			
			var duplicate = false;
			this._getDuplicate = function() { return duplicate; };
			this._setDuplicate = function(newDuplicate) { duplicate = newDuplicate; };
		};
		
		Message.prototype = {
			get payloadString() { return this._getPayloadString(); },
			get payloadBytes() { return this._getPayloadBytes(); },
			
			get destinationName() { return this._getDestinationName(); },
			set destinationName(newDestinationName) { this._setDestinationName(newDestinationName); },
			
			get qos() { return this._getQos(); },
			set qos(newQos) { this._setQos(newQos); },
	
			get retained() { return this._getRetained(); },
			set retained(newRetained) { this._setRetained(newRetained); },
	
			get duplicate() { return this._getDuplicate(); },
			set duplicate(newDuplicate) { this._setDuplicate(newDuplicate); }
		};
		   
		// Module contents.
		return {
			Client: Client,
			Message: Message
		};
	})(window);
	
	
	// 把模块放到全局命名空间中去
	(function(){
		return (typeof global !== "undefined") ? global :
			(typeof self !== "undefined") ? self :
			(typeof window !== "undefined") ? window : {};
	})()["Paho"] = Paho;
	
}